Shape memory performance of green in situ polymerized nanocomposites based on polyurethane/graphene nanoplatelets: Synthesis, properties, and cell behavior

Nowadays, developing biocompatible shape memory polymers is among major expanding topics in medical applications. In this study, novel biocompatible polyurethane/graphene nanoplatelet (PU/GNp) nanocomposites were synthesized from poly(epsilon-caprolactone)diol (PCL diol)/Castor oil and Hexamethylene diisocyanate (HDI) through in situ polymerization. Three different %wt. of GNp were incorporated into the polyol mixtures to monitor the effect of nano fillers on the shape memory behavior of PUs. The chemical structure of nanocomposites was studied by Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopies. X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM), and differential scanning calorimetry (DSC) were used to evaluate the nanocomposites properties. GNp incorporation affected the bulk morphology as well as thermal properties and crystallinity. Dynamic mechanical thermal analysis (DMTA) revealed the higher elastic modulus values for nanocomposites compared to the pure PU. The biocompatibility of PU/GNp nanocomposites was investigated via MTT assay. Finally, based on shape memory studies, the higher crystallinity, and improved elastic modulus of the nanocomposites resulted in their excellent shape fixity (about 91-96%) and shape recovery (95-99%) behaviors. According to the results, the prepared PU/GNp nanocomposites can be considered as potential choices for applicable shape memory devices for biomedical applications. POLYM. COMPOS., 39:4020-4033, 2018. (c) 2017 Society of Plastics Engineers